Engine Immobilizer System - Diagnostics Lexus GX J120

HOW TO PROCEED WITH TROUBLESHOOTING

HINT

Troubleshoot in accordance with the procedures on the following references.

1. VEHICLE BROUGHT TO WORKSHOP Go to next step.
2. CUSTOMER PROBLEM ANALYSIS CHECK AND PROBLEM SYMPTOM CONFIRMATION Go to next step.
3. CRANK ENGINE FOR MORE THAN 10 SECONDS Go to next step.
4. CHECK DTC Check for a DTC. When any of codes B2780, B2784, B2793, B2794, B2795, B2796, B2797, B2798 or B2799 is output, proceed to A. When a code except B2780, B2784, B2793, B2794, B2795, B2796, B2797, B2798 or B2799 is output, proceed to B. B: Go to SFI SYSTEM (See «PRECAUTION»(/lexus/gx/j120-2002-2009/remont/testing-diagnostics/#sfi-system-2uz-fe-diagnostics) ) A: Go to next step.
5. READ VALUE OF HAND-HELD TESTER (IMMOBILIZER ECU (TRANSPONDER KEY ECU ASSY) (SWITCH CONDITION)) Connect the hand-held tester to the DLC3. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the item "KEY SW" in the "DATA LIST" and read its value displayed on the hand-held tester. Transponder key ECU assy: TRANSPONDER KEY ECU ASSY Item Measurement item/Display (Range) Normal condition Diagnostic note Key SW Unlock warning switch signal/ON or OFF OFF: Key is in IG key cylinder ON: No key is in IG key cylinder - NG: Go to DTC B2780 (See «DTC B2780 PUSH SWITCH/KEY UNLOCK WARNING SWITCH MALFUNCTION»(/lexus/gx/j120-2002-2009/remont/door-locks-anti-theft-systems/#engine-immobilizer-system-diagnostics) ) OK: Go to next step.
6. See «PROBLEM SYMPTOMS TABLE»(/lexus/gx/j120-2002-2009/remont/door-locks-anti-theft-systems/#engine-immobilizer-system-diagnostics) When problem is not listed on problem symptoms table, proceed to A. When problem is listed on problem symptoms table, proceed to B. B Go to step 8 . A: Go to next step.
7. PERFORM TROUBLESHOOTING ACCORDING TO MALFUNCTION SYMPTOM See «PRE-CHECK»(/lexus/gx/j120-2002-2009/remont/door-locks-anti-theft-systems/#engine-immobilizer-system-diagnostics) Inspect with the hand-held tester (ECU DATA MONITOR). Inspect with the hand-held tester (ACTIVE TEST). See «TERMINALS OF ECU»(/lexus/gx/j120-2002-2009/remont/door-locks-anti-theft-systems/#engine-immobilizer-system-diagnostics) Go to next step.
8. ADJUST, REPAIR OR REPLACE END

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1. DIAGNOSIS SYSTEM Description The ECM controls the function of the immobilizer system on this vehicle. Data of the immobilizer system and the Diagnostic Trouble Code (DTC) can be read in the Data Link Connector 3 (DLC3) of the vehicle. When trouble occurs in the immobilizer system, even though the Malfunction Indicator Lamp (MIL) does not come on, DTCs can be checked. Therefore, when there seems to be trouble with the immobilizer system, use the hand-held tester to check for trouble and troubleshoot it. Inspect the DLC3. The vehicle's ECM uses the ISO 9141-2 communication protocol. The terminal arrangement of the DLC3 complies with SAE J 1962 and matches the ISO 9141-2 format. Standard: DLC3 Terminal No. Condition Specified Condition 7 (Bus + Line) <=> 5 (Signal ground) During communication Pulse generation 4 (Chassis Ground) <=> Body ground Constant 1 ohms or less 5 (Signal Ground) <=> Body ground Constant 1 ohms or less 16 (B+) <=> Body ground Constant 9 - 14 V HINT: If the display shows "UNABLE TO CONNECT TO VEHICLE" when you have connected the cable of the hand-held tester to the DLC3, turned the ignition switch ON and operated the hand-held tester, the problem may be on the vehicle side or the tester side. If communication is normal when the tester is connected to other vehicle, inspect the DLC3 of the original vehicle. If communication is still impossible when the tester is connected to another vehicle, the problem may be in the tester itself, so consult the Service Department listed in the tester's instruction manual.
2. INSPECT DIAGNOSIS Using the hand-held tester, check for DTC. NOTE: Hand-held tester only: When the diagnosis system is switched from the normal mode to the check mode, all the DTCs and freeze frame data recorded in the normal mode are erased. So before switching modes, always check the DTCs and freeze frame data, and make a note of them. Prepare the hand-held tester. Connect the hand-held tester to the DLC3 under the instrument panel lower pad. Turn the ignition switch ON and push the hand-held tester switch ON. Use the hand-held tester to check for DTCs and freeze frame data, and make a note of them (For operating instructions, see the hand-held tester instruction book). Confirm the details of the DTCs. Either of the following procedures will erase the DTCs and freeze frame data. Operating the hand-held tester to erase the codes (See the hand-held tester instruction book for operating instructions). Disconnecting the battery terminals or ECU-B fuse.
3. DATA LIST HINT: According to the DATA LIST displayed by the hand-held tester, you can read the value of the switch, sensor, actuator, etc. without parts removal. Reading the DATA LIST as the first step of troubleshooting is one way to shorten labor time. Connect the hand-held tester to the DLC3. Turn the ignition switch ON. According to the display on the tester, read the DATA LIST. Transponder key ECU assy: DATA LIST Item Measurement Item/Display (Range) Normal Condition Diagnostic Note KEY SW Unlock warning SW signal/ ON or OFF OFF: Key is in IG key cylinder - KEY SW Unlock warning SW signal/ ON or OFF ON: No key is in IG key cylinder - IG SW IG SW signal/ ON or OFF OFF: IG SW is ON or START position - IG SW IG SW signal/ ON or OFF ON: IG SW is OFF or ON position - IMMOBILIZER Immobilizer system status/SET or UNSET UNSET: Without key - IMMOBILIZER Immobilizer system status/SET or UNSET SET: Ignition switch ON - RESPONSE - NG/OK - FRAME - NG/OK - SERIAL NUMBER - NG/OK - ENCRYPT CODE - NG/OK - STATUS - NG/OK - BCC - NG/OK - SUB KEY - NO MATCH/MATCH - MASTER KEY - NO MATCH/MATCH - REGIST SUB CODE Number of registered master key/min. 0, max. 15 Number of registered master key - REGIST MAS CODE Number of registered sub-key/min. 0, max. 15 Number of registered sub-key - REG CODE SPACE - NOT FUL/FULL - +B - NORMAL/BREAK - ANTENNA COIL - NORMAL/FAIL - G-CODE SUPPORT - NOT SUP/SUPPORT
4. ACTIVE TEST HINT: Performing the ACTIVE TEST using the hand-held tester allows you to operate the relay, VSV, actuator, etc. without parts removal. Performing the ACTIVE TEST as the first step of troubleshooting is one of the methods to shorten labor time. It is possible to display the DATA LIST during the ACTIVE TEST. Connect the hand-held tester to the DLC3. Turn the ignition switch ON. According to the display on the tester, perform the ACTIVE TEST. Transponder key ECU assy: ACTIVE TEST Item Test Details Diagnostic Note SECURITY INDIC Turn security indicator ON/OFF Key reminder buzzer is installed in combination meter

DIAGNOSTIC TROUBLE CODE TABLE

DIAGNOSTIC TROUBLE CODE TABLE

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1. TRANSPONDER KEY ECU DTC TABLE
2. ECM DTC TABLE NOTE: The DTC for the immobilizer system is specified. If the other codes are output, check «DIAGNOSTIC TROUBLE CODE TABLE»(/lexus/gx/j120-2002-2009/remont/testing-diagnostics/#sfi-system-2uz-fe-diagnostics) of the SFI system.

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1. CHECK TRANSPONDER KEY AMPLIFIER Disconnect the I17 amplifier connector, and check the continuity of each terminal of the wire harness side connector. Standard: TRANSPONDER KEY AMPLIFIER (DISCONNECTED) Symbols (Terminal No.) Wiring Color Condition Specified Condition GND (I17-7) <=> Body ground BR<=> - Constant Continuity If the result is not as specified, there may be a malfunction on the wire harness side. Reconnect the I17 amplifier connector, and check the continuity or voltage of each terminal of the connector. Standard: TRANSPONDER KEY AMPLIFIER (RECONNECTED) Symbols (Terminal No.) Wiring Color Condition Specified Condition VC5 (I17-7) <=> GND (I17-7) R <=> BR No key in ignition key cylinder -> With key 0 V -> 10 - 14 V CODE (I17-4) <=> GND (I17-7) Y <=> BR No key in ignition key cylinder -> With key Waveform (1) TXCK (I17-5) <=> GND (I17-7) Y-B <=> BR No key in ignition key cylinder -> With key Waveform (2) GND (I17-7) <=> Body ground BR <=> - Constant Continuity If the result is not as specified, the amplifier may have a malfunction. Inspect using an oscilloscope. WAVEFORM 1 (REFERENCE) Terminal CODE - GND Tool setting 10 V/DIV, 20 ms/DIV Condition Ignition switch ON WAVEFORM 2 (REFERENCE) Terminal TXCK <=> GND Tool setting 5 V/DIV., 20 ms/DIV. Condition Ignition switch ON
2. CHECK TRANSPONDER KEY ECU ASSY Disconnect the T9 ECU connector, and check the voltage or continuity between each terminal of the wire harness side connector. Standard: TRANSPONDER KEY ECU ASSY (DISCONNECTED) Symbols (Terminal No.) Wiring Color Condition Specified Condition GND (T9-14) <=> Body ground W-B <=> - Constant Continuity +B (T9-1) <=> GND (T9-14) W-R <=> W-B Constant 10 - 14 V IG (T9-2) <=> GND (T9-14) B-R <=> W-B Ignition switch OFF -> ON 0 V -> 10 - 14 V KSW (T9-10) <=> GND (T9-14) G-Y <=> W-B No key in ignition key cylinder -- With key No continuity °Continuity AGND (T9-13) <=> Body ground BR <=> - Constant Continuity If the result is not as specified, there may be a malfunction on the wire harness side. Reconnect the T9 ECU connector, and check the voltage between each terminal of the connector. Standard: TRANSPONDER KEY ECU ASSY (RECONNECTED) Symbols (Terminal No.) Wiring Color Condition Specified Condition KSW (T9-10) <=> GND (T9-14) G-Y <=> W-B No key in ignition key cylinder -> With key 10 - 14 V - 0 V VC5 (T9-8) <=> GND (T9-14) R <=> W-B Ignition switch OFF -> ON 0 V -> 10 - 14 V TXCT (T9-12) <=> GND (T9-14) Y-B <=> W-B Ignition switch OFF -> ON Waveform (1) CODE (T9-11) <=> GND (T9-14) Y <=> W-B Ignition switch OFF -> ON Waveform (2) EFIO (T9-6) <=> GND (T9-14) W-R <=> W-B Ignition switch OFF --> ON Waveform (3) EFII (T9-7) <=> GND (T9-14) L-R <=> W-B Ignition switch OFF --> ON Waveform (4) CTY (T9-4) <=> GND (T9-14) R-Y <=> W-B Driver side door CLOSED --> OPEN 10 - 14 V -> 0 V IND (T9-3) <=> GND (T9-14) V-W <=> W-B During set preparation 10 - 14V -> 0 V (Waveform) If the result is not as specified, the transponder key ECU assy may have a malfunction. Inspect using an oscilloscope. WAVEFORM 1 (REFERENCE) Terminal TXCT <=> GND Tool setting 5 V/DIV., 20 ms/DIV. Condition Ignition switch ON WAVEFORM 2 (REFERENCE) Terminal CODE <=> GND Tool setting 10 V/DIV., 20 ms/DIV. Condition Ignition switch ON WAVEFORM 3 (REFERENCE) Terminal EFIO <=> GND Tool setting 10 V/DIV, 20 ms/DIV. Condition Ignition switch ON WAVEFORM 4 (REFERENCE) Terminal EFII <=> GND Tool setting 10 V/DIV, 20 ms/DIV. Condition Ignition switch ON
3. CHECK ECM Disconnect the E7 and E8 ECM connectors, and check the voltage or continuity between each terminal of the wire harness side connectors. Standard: ECM Symbols (Terminal No.) Wiring Color Condition Specified Condition IMI (E8-16) <=> E1 (E7-1) W-R <=> BR No key in ignition key cylinder -> With key Waveform (1) IMO (E8-15) <=> E1 (E7-1) L-R <=> BR No key in ignition key cylinder -> With key Waveform (2) E1 (E7-1) <=> Body ground BR <=> - Constant Continuity If the result is not as specified, there may be a malfunction on the wire harness side. Inspect using an oscilloscope. WAVEFORM 1 (REFERENCE) Terminal IMI <=> GND Tool setting 10 V/DIV., 20 ms/DIV. Condition Ignition switch ON WAVEFORM 2 (REFERENCE) Terminal IMO <=> GND Tool setting 5 V/DIV., 5 ms/DIV. Condition Ignition switch ON

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CIRCUIT DESCRIPTION

This DTC will be output if the transponder key ECU does not detect that the unlock warning switch is ON even when the ignition switch is ON (Under the normal condition, the unlock warning switch is ON when the ignition switch is ON).

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INSPECTION PROCEDURE

HINT

Start the inspection from step 1 when using the hand-held tester and start from step 2 when not using the hand-held tester.

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1. READ VALUE OF HAND-HELD TESTER (TRANSPONDER KEY ECU (SWITCH CONDITION)) Connect the hand-held tester to the DLC3. Turn the ignition switch ON with the key that will not start the engine. Select the item "KEY SW" on the hand-held tester. OK: OFF -> Key is in IG key cylinder ON -> No key is in IG key cylinder OK: REPLACE TRANSPONDER KEY ECU ASSY NG: Go to next step.
2. INSPECT UNLOCK WARNING SWITCH ASSY Remove the unlock warning switch. Inspect the unlock warning switch continuity. Standard: UNLOCK WARNING SWITCH ASSY Terminal No. Condition Specified Condition 1 <=> 2 Switch pushed (Key removed) Continuity 1 <=> 2 Switch free (Key set) No continuity NG: REPLACE UNLOCK WARNING SWITCH ASSY OK: Go to next step.
3. CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSY <=> UNLOCK WARNING SWITCH) Disconnect the T9 ECU and K3 unlock warning switch connectors. Check the continuity between the wire harness side connectors. Standard: TRANSPONDER KEY ECU ASSY <=> UNLOCK WARNING SWITCH Symbols (Terminal No.) Specified Condition KSW (T9-10) <=> - (K3-2) Continuity NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: REPLACE TRANSPONDER KEY ECU ASSY

The transponder key coil is built into the transponder key amplifier and receives a key code signal from the transponder chip in the key. This signal is amplified by the amplifier, then it is output to the transponder key ECU.

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HINT

Start the inspection from step 1 when using the hand-held tester and start from step 2 when not using the hand-held tester.

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1. READ VALUE OF HAND-HELD TESTER (IMMOBILIZER ECU (TRANSPONDER KEY ECU ASSY) (SWITCH CONDITION)) Connect the hand-held tester to the DLC3. Turn the ignition switch ON with the key with which the engine does not start. Select the item "ANTENNA COIL" on the hand-held tester. OK: NORMAL NG: FAIL OK: CHECK AND REPLACE TRANSPONDER KEY ECU ASSY NG: Go to next step.
2. CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSY <=> TRANSPONDER KEY AMPLIFIER) (TRANSPONDER KEY ECU ASSY OR TRANSPONDER KEY AMPLIFIER <=> BODY GROUND) Disconnect the T9 ECU and I17 amplifier connectors. Check the continuity between the wire harness side connectors. Standard: TRANSPONDER KEY ECU ASSY <=> TRANSPONDER KEY AMPLIFIER Symbols (Terminal No.) Specified Condition VC5 (T9-8) <=> VC5 (I17-1) Continuity CODE (T9-11) <=> CODE (I17-4) Continuity TXCT (T9-12) <=> TXCT (I17-5) Continuity AGND (T9-13) <=> GND (I17-7) Continuity Check the continuity between the T9 ECU or I17 amplifier wire harness side connector and body ground. Standard: TRANSPONDER KEY ECU ASSY OR TRANSPONDER KEY AMPLIFIER <=> BODY GROUND Symbols (Terminal No.) Specified Condition VC5 (T9-8) or VC5 (I17-1) <=> Body ground No continuity CODE (T9-11) or CODE (I17-4) <=> Body ground No continuity TXCT (T9-12) or TXCT (I17-5) <=> Body ground No continuity AGND (T9-13) or GND (I17-7) <=> Body ground No continuity NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: REPLACE TRANSPONDER KEY AMPLIFIER

This DTC is output when trouble is found in a key during the key code registration or the key code is not registered normally. Replace the key when the key code registration is not performed normally and this DTC is detected.

TRANSPONDER CHIP MALFUNCTION

1. CHECK DTC Delete the DTC. Insert the key into the ignition key cylinder. Check that no code is output. OK: NO PROBLEM NG: Go to next step.
2. RE-REGISTER KEY Delete the DTC. Re-register the key, and check that the engine starts with the key. OK: NORMAL NG: REPLACE KEY

This DTC is output when a key with an incomplete key code is inserted into the ignition key cylinder.

UNMATCHED ENCRYPTION CODE

1. REPLACE KEY

This DTC is output when a key with a key code that has not been registered in the ECU is inserted into the ignition key cylinder.

UNMATCHED KEY CODE

1. DELETE DTC AND INSERT ALL PRESENTLY AVAILABLE KEYS TO CHECK WHETHER ENGINE STARTS OR NOT OK: NO PROBLEM (BECAUSE OF KEY RE-REGISTRATION) NG: REPLACE KEY WITH WHICH ENGINE DOES NOT START

This DTC is stored in the memory when a key that does not have a transponder chip is inserted or if communication between the key and transponder key ECU is impossible.

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HINT

Start the inspection from step 1 when using the hand-held tester and start from step 2 when not using the hand-held tester.

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1. READ VALUE OF HAND-HELD TESTER (IMMOBILIZER ECU (TRANSPONDER KEY ECU ASSY) (SWITCH CONDITION)) Connect the hand-held tester to the DLC3. Turn the ignition switch ON with the key that will not start the engine. Select the item "IMMOBILIZER" on the hand-held tester. OK: SET -> Ignition switch ON UNSET -> Without key OK: NORMAL NG: Go to next step.
2. CHECK WHETHER ENGINE STARTS WITH OTHER KEYS Check whether the engine starts with the other keys for the vehicle. OK: RE-REGISTER OR REPLACE KEY WITH WHICH ENGINE DOES NOT START NG: Go to next step. HINT: Start the inspection from step 3 when using the hand-held tester and start from step 4 when not using the hand-held tester.
3. READ VALUE OF HAND-HELD TESTER (IMMOBILIZER ECU (TRANSPONDER KEY ECU ASSY) (SWITCH CONDITION)) Connect the hand-held tester to the DLC3. Turn the ignition switch ON with the key with which the engine does not start. Select the item "ANTENNA COIL" on the hand-held tester. OK: NORMAL NG: FAIL NG: CHECK AND REPLACE TRANSPONDER KEY ECU ASSY OK: Go to next step.
4. CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSY <=> TRANSPONDER KEY AMPLIFIER) (TRANSPONDER KEY ECU ASSY OR TRANSPONDER KEY AMPLIFIER <=> BODY GROUND) Disconnect the T9 ECU and I17 amplifier connectors. Check the continuity between the wire harness side connectors. Standard: TRANSPONDER KEY ECU ASSY <=> TRANSPONDER KEY AMPLIFIER Symbols (Terminal No.) Specified Condition VC5 (T9-8) <=> VC5 (I17-1) Continuity CODE (T9-11) <=> CODE (I17-4) Continuity TXCT (T9-12) <=> TXCT (I17-5) Continuity AGND (T9-13) <=> GND (I17-7) Continuity Check the continuity between the T9 ECU or I17 amplifier wire harness side connector and body ground. Standard: TRANSPONDER KEY ECU ASSY OR TRANSPONDER KEY AMPLIFIER <=> BODY GROUND Symbols (Terminal No.) Specified Condition VC5 (T9-8) or VC5 (I17-1) <=> Body ground No continuity CODE (T9-11) or CODE (I17-4) <=> Body ground No continuity TXCT (T9-12) or TXCT (I17-5) <=> Body ground No continuity AGND (T9-13) or GND (I17-7) <=> Body ground No continuity NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step.
5. CHECK OPERATION OF TRANSPONDER KEY AMPLIFIER After replacing the transponder key amplifier, check that the engine starts. NG: NORMAL (TRANSPONDER KEY AMPLIFIER DEFECTIVE) OK: REPLACE TRANSPONDER KEY ECU ASSY

This DTC is output when an error occurs in the normal communication.

HINT

Some noise exists in the communication line.

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1. CHECK OPERATION OF TRANSPONDER KEY AMPLIFIER

1. After replacing the transponder key amplifier, check that the engine starts. OK: NORMAL (TRANSPONDER KEY AMPLIFIER DEFECTIVE) NG: REPLACE TRANSPONDER KEY ECU ASSY

This DTC is output when the ECM detects errors in the communication between the transponder key ECU assy and the ECM, or in the communication lines.

This DTC is also output when an engine start is attempted while the ECU communication ID between the transponder key ECU assy and the ECM are different.

Before troubleshooting for this DTC, make sure that there is no DTC detected in the transponder key ECU.

If there is key code-related DTC detected in the transponder key ECU assy, repair it first.

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1. CHECK WIRE HARNESS (TRANSPONDER KEY ECU ASSY <=> ECM) (TRANSPONDER KEY ECU ASSY OR ECM <=> BODY GROUND) Disconnect the T9 ECU and E8 ECM connectors. Check the continuity between the wire harness side connectors. Standard: TRANSPONDER KEY ECU ASSY <=> ECM Symbols (Terminal No.) Specified Condition EFIO (T9-6) <=> IMI (E8-16) Continuity EFII (T9-7) <=> IMO (E8-15) Continuity Check the continuity between the T9 or E8 wire harness side connector and body ground. Standard: TRANSPONDER KEY ECU ASSY OR ECM <=> BODY GROUND Symbols (Terminal No.) Specified Condition EFIO (T9-6) or lMI (E8-16) <=> Body ground No continuity EFII (T9-7) or IMO (E8-15) <=> Body ground No continuity NG: REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step.
2. CHECK OPERATION OF TRANSPONDER KEY AMPLIFIER After replacing the transponder key amplifier, check that the engine starts. NG: NORMAL (TRANSPONDER KEY AMPLIFIER DEFECTIVE) OK: REPLACE TRANSPONDER KEY ECU ASSY

See also:
• PRECAUTION
• DTC B2780 PUSH SWITCH/KEY UNLOCK WARNING SWITCH MALFUNCTION